Construction drawings in Hillingdon

Article 4, conservation and heritage in Hillingdon

Hillingdon publishes 33 conservation areas and 150 Article 4 directions. Historic England lists 436 entries, and 45 appear on the Heritage at Risk register.

An Article 4 direction takes away permitted development rights for specific works in a defined area, so what would be permitted elsewhere needs an application here. The plan is therefore set in a clear order. We confirm the planning route, secure the decision, and then issue construction drawings that follow the approved scheme.

Converting a house into several lets brings its own planning question, which we check against the council's directions, and it needs a technical set that deals with fire separation and sound.

We read each direction against your own boundary. Some cover a street frontage, some a whole estate, and some only particular alterations such as front porches or roof changes, so the answer for a given house is rarely obvious from the borough figure alone.

Green belt, large plots and the local plan

Green belt covers 42 per cent of the borough, and houses within it face stricter rules on the size of additions, judged against the original building. Hillingdon's plan is the Hillingdon Local Plan Part 1: Strategic Policies, with Local Plan Part 2: Development Management Policies and Site Allocations and Designations (January 2020), and the council's Part 2 document sets out the development management policies applied to householder schemes.

Because additions in the green belt are measured against volume, the technical set has to be exact. We state the floor area and volume of the proposed work on the sheets, along with the existing figure, so that no site decision pushes the scheme beyond what the council approved.

Large plots also bring outbuildings. A garden room, studio or gym near the boundary has its own fire-distance rules, its own electrical supply and often its own drainage, and our drawings cover them in the same set as the house extension.

Flat-roofed side extensions, common on interwar semis, need particular care at the junction with the original roof. We show the lead flashing, the upstand and the insulation falls in section, because a leak at that junction is hard to trace once the ceiling is finished.

Volume of work and timing in Hillingdon

Hillingdon decided 1,147 householder applications in its latest year, and granted 90.2 per cent. Householder decisions made on time or within an agreed extension were 94.3 per cent.

The council also issued 529 lawful development certificates in the data period, and decided 29 larger-extension prior approvals in favour against 13 refused. Prior approval is clearly a working route here, as it can be much faster than a householder application when neighbours do not object.

68.9 per cent of households live in a house or bungalow and 56.6 per cent own their home, so the typical client is a family planning to stay and invest. We draw sets that last, with thermal specifications that reach the limits in the table and details that will not need reworking.

Hillingdon's mix of suburban estates and village edges means the same service reads differently from one address to the next. A detached house with a long drive needs a vehicle-access note for the builder, and a semi with a shared side passage needs a party-wall and access discussion before scaffolding goes up.

What the set includes and where to go next

The set includes structural plans, foundation details, junction sections, window and door schedules, drainage, ventilation and a specification against Approved Document L. Our structural calculations feed the beams and footings, and a second technologist reads each sheet before it is issued. We revise the drawings free of charge if the council or an inspector asks.

The borough overview is at architectural drawings in Hillingdon, and the approval stage is at building regulations drawings in Hillingdon. We also draw in Three Rivers, Ealing and Hounslow, and explain the service at construction drawings in London.